Don't change FLOAT(X+1,X) to FLOAT(X+2,X)

Docs/manual.texi:
  ChangeLog
mysql-test/r/show_check.result:
  Updated test for SHOW COLUMNS
mysql-test/t/show_check.test:
  Updated test for SHOW COLUMNS

Docs/manual.texi

@@ -46857,7 +46857,7 @@ users use this code as the rest of the code and because of this we are
 not yet 100% confident in this code.
 
 @menu
-* News-3.23.51::                
+* News-3.23.51::                Changes in release 3.23.51
 * News-3.23.50::                Changes in release 3.23.50
 * News-3.23.49::                Changes in release 3.23.49
 * News-3.23.48::                Changes in release 3.23.48
@@ -46915,6 +46915,10 @@ not yet 100% confident in this code.
 @node News-3.23.51, News-3.23.50, News-3.23.x, News-3.23.x
 @appendixsubsec Changes in release 3.23.51
 @itemize @bullet
+@item
+Fixed the @code{FLOAT(X+1,X)} is not converted to @code{FLOAT(X+2,X)}.
+(This also affected @code{DECIMAL}, @code{DOUBLE} and @code{REAL} types)
+@item
 Fixed the result from @code{IF()} is case in-sensitive if the 2 and
 third arguments are case sensitive.
 @end itemize

mysql-test/r/show_check.result

@@ -92,3 +92,19 @@ t1	CREATE TABLE `t1` (
   `a` int(11) NOT NULL default '0',
   PRIMARY KEY  (`a`)
 ) TYPE=MyISAM
+Field	Type	Null	Key	Default	Extra
+a	decimal(9,2)	YES		NULL	
+b	decimal(9,0)	YES		NULL	
+e	double(9,2)	YES		NULL	
+f	double(5,0)	YES		NULL	
+h	float(3,2)	YES		NULL	
+i	float(3,0)	YES		NULL	
+Field	Type	Null	Key	Default	Extra
+c	decimal(10,0)	YES		NULL	
+d	double	YES		NULL	
+f	float	YES		NULL	
+r	double	YES		NULL	
+Field	Type	Null	Key	Default	Extra
+c	decimal(4,3)	YES		NULL	
+d	double(4,3)	YES		NULL	
+f	float(4,3)	YES		NULL	

mysql-test/t/show_check.test

@@ -73,3 +73,17 @@ drop table t1;
 create table t1 (a int not null, primary key (a));
 show create table t1;
 drop table t1;
+
+create table t1 (a decimal(9,2), b decimal (9,0), e double(9,2), f double(5,0), h float(3,2), i float(3,0));
+show columns from t1;
+drop table t1;
+
+# Check auto conversions of types
+
+create table t1 (c decimal, d double, f float, r real);
+show columns from t1;
+drop table t1;
+
+create table t1 (c decimal(3,3), d double(3,3), f float(3,3));
+show columns from t1;
+drop table t1;

sql/sql_parse.cc

@@ -2432,9 +2432,9 @@ bool add_field_to_list(char *field_name, enum_field_types type,
   uint sign_len=type_modifier & UNSIGNED_FLAG ? 0 : 1;
 
   if (new_field->length && new_field->decimals &&
-      new_field->length < new_field->decimals+2 &&
+      new_field->length < new_field->decimals+1 &&
       new_field->decimals != NOT_FIXED_DEC)
-    new_field->length=new_field->decimals+2; /* purecov: inspected */
+    new_field->length=new_field->decimals+1; /* purecov: inspected */
 
   switch (type) {
   case FIELD_TYPE_TINY: